X-ray apparatus

ABSTRACT

X-ray apparatus provided with an excessive-size indication which gives a signal to the radiologist when the cross-sectional area of the beam used for fluoroscopic examination exceeds the size of the radiograph to be made.

United States Patent 1191 1 1 3,875,411 Kunert 145] Apr. 1, 1975 1 1X-RAY APPARATUS 3.502.378 3/1970 Stewart 250/512 3,581,094 5/1971 Pe ser250/511 Hem? Amselweg- 3.043.095 2/1972 Shiister 250/514 Germany [73]Assignee: U. S. Philips Corporation, New

York; N.Y. Primary E.\'aminer.1ames W. Lawrence Assistant Examiner-C. E.Church Filed 1973 Attorney, Agent, or Firm-Frank R. Trifari 1211 Appl.N0.: 392,754

[30] Foreign Application Priority Data Sept. 30, 1972 Germany 2248101[57] ABSTRACT 52 us. 01 250/402, 250/415, 250/511 X-ray apparatusProvided with an excessive-size indi- 151 1m. (:1. G031) 41/16 cationwhich gives a Signal to the radiologist when the [58] Fi ld of S h250/402 416 51 1 512 cross-sectional area of the beam used forfluoroscopic 250 513 5 4 examination exceeds the size of the radiographto be made. 156] References Cited UNITED STATES PATENTS 3 Claims, 2Drawing Figures 3.2001104 9/1965 Burche11 250/512 X-RAY APPARATUS Theinvention relates to an X-ray apparatus having a first pair of diaphragmblades which are adapted to be displaced by a motor and serve to limitan X-ray beam in the horizontal direction and a second pair of diaphragmblades which are adapted to be displaced by a motor and serve to limitthe X-ray beam in the vertical direction. a servo-control system beingprovided for displacing the diaphragm blades so as to limit the beam toa size required for making a radiograph, in which a motor displaces thediaphragm blades until a direct voltage which depends upon the positionsof the associated diaphragm blades corresponds to a control voltagewhich depends upon the size of the radiograph to be made, said X-rayapparatus being further provided with a control device for displacingthe diaphragm blades independently of the size of the radiograph to bemade.

Such an apparatus is described in principle in US. Pat. No. 3,502,878.Usually radiography is preceded by fluoroscopy. and the setting of thediaphragm may be different in the two processes. In this case, beforethe commencement of radiography the diaphragm is set to the requiredsize by means of the servo-control system. A disadvantage of thisautomatic change-over to the setting required for radiography is thatwhen the fluorescopic image previously set by the radiologist is greaterthan the size of the radiograph, under certain circumstances detailsessential for diagnosis then are not recorded. However, this will beperceived only after development of the radiograph. It is an object ofthe present invention to provide a design for an apparatus of theaforementioned kind such that during fluoroscopy the radiologist isgiven an indication when the size of the radiograph is smaller than thesize of the image on the fluoroscope as set by the radiologist duringfluoroscopy.

According to the invention this problem is solved in that a comparisondevice is provided which is arranged to compare the direct voltageswhich on operation of the control devices, result from the positions ofthe diaphragm blades with the control voltages and to control anindicating device, the arrangement being such that an indication isgiven when the height or the width of the size of the radiograph to bemade is smaller than the corresponding dimension of the X-ray beam aslimited by the diaphragm.

The invention will now be described, by way ofexample, with reference toan embodiment shown in the accompanying diagrammatic drawings, in whichFIG. 1 is a simplified block-schematic diagram of a known X-rayapparatus, and

FIG. 2 is an embodiment ofa circuit arrangement according to theinvention to be added to the apparatus shown in FIG. 1.

Referring now to FIG 1, an X-ray apparatus comprises two pairs ofdiaphragm blades 11 and 21, which are inserted in the ray path anddetermine the width and the height respectively of the X-ray beam. Thediaphragm blades are displaceable by means of motors 12 and 22. Thesemotors are controlled by control amplifiers l3 and 23 respectively. Inaddition, the motors l2 and 22 each displace a tapping on apotentiometer 14 and 24 respectively connected to the input of theassociated control amplifier 13 and 23 respectively. The controlamplifiers 13 and 23 each compare the voltage set up at the tapping onthe potentiometer 14 and 24 respectively (actual value) with anothervoltage (desired value), the motors l2 and 22 each running in adirection such that the said other voltage becomes equal to the voltageset up at the potentiometer 14 and 24 respectively. The resultingpositions of the diaphragm blade pairs 11 and 21 consequently eachdepend upon the value of the voltage which via a switch 17 and 27respectively is applied to the control amplifier 13 and 23 respectively,the said switches each connecting the input of the associated controlamplifier either to the tapping on a potentiometer l5 and 25respectively or to a signalling source 16 and 26 respectively.

The signalling sources 16 and 26 each supply a direct voltage which isdependent upon the width and the height respectively of the size of theradiograph (which width and height are determined by the width and theheight respectively of the cassette and by the preselected division).Thus the cross-sectional area of the X-ray beam as limited by thediaphragm 11, 21 corresponds to the size of the radiograph when theswitches 17 and 27 establish connections to the signalling sources 16and 26 respectively. If on the other hand the inputs of the controlamplifiers l3 and 23 are connected via the switches 17 and 27respectively to the tappings on the potentiometers 15 and 25respectively, the radiologist can himself determine the cross sectionalarea of the X-ray beam by displacing the tappings on the otentiometers.

Usually radiography is preceded by fluoroscopy, permitting theradiologist to obtain optimum setting of the diaphragm by displacing thetappings on the potentiometers l5 and 25 whilst looking at the image onthe fluoroscope. On termination of the fluoroscopic examination theswitches 17 and 27 are automatically changed over to the signal sources16 and 26, so that before radiography is started the diaphragm isautomatically set to the size required for making a radiograph.

FIG. 2 shows a comparison circuit (comparator) l to which are applied avoltage U which is derived from the tapping on the potentiometer l4 andis proportional to the width of the fluoroscopic image and a controlvoltage U which is supplied by the signalling source 16 and isproportional to the width of the size of the radiograph. Similarly avoltage U which is derived from the tapping on the potentiometer 24 andis proportional to the height of the fluoroscopic image and a controlvoltage U supplied by the signalling source 26 are applied to acomparison device 2. The comparison devices 1 and 2 each provide abinary output signal, i.e. a logic signal l if the voltage U and Urespectively exceeds the control voltage U and U respectively and alogic signal 0" if the voltage U and U respectively is smaller than, orequal to, the control voltage U and U respectively, The out puts of thecomparison devices 1 and 2 are connected to an OR-gate 3 the outputcircuit of which includes an indicating lamp 4. The lamp will beilluminated if to at least one of the inputs a 1" is applied, i.e. whenthe width and/or the height of the fluoroscopic image exceeds thecorresponding dimension of the size of the radiograph to be made.

When the potentiometer tappings 14 and 24 are coupled to the motors 12and 22 so that the voltages derived from them are a maximum in theclosed positions of the diaphragm blades 11 and 21, the voltages U and Uare smaller than the control voltages U and U respectively when thewidth or the height respectively of the fluoroscopic image is greaterthan that of the size of the radiograph to be made. In this case thecomparison devices must supply the logic signal 1 when the voltage U 38or U is smaller than the control voltage U KB or U K respectively.

The invention may be used in X-ray apparatus in which thecross-sectional area of the X-ray beam is limited by a diaphragmprovided on the cassette-holder of the apparatus (secondary diaphragm)and in X-ray apparatus in which the cross sectional area of the X-raybeam is limited by a diaphragm mounted on the X-ray tube and henceremote from the film (primary diaphragm); in the latter case the settingof the diaphragm ll, 21 required for a predetermined size of aradiograph and hence the values of the control voltages U and U dependupon the spacing between the diaphragm and the cassette holder of theX-ray apparatus, so that these voltages are to be varied with variationof this spacing in a known manner (see for example US. Pat. Nos. 3511995and 3,502.878).

Although the invention has been described with reference to an X-rayapparatus in which the displacement of the diaphragm blades (by means ofthe potentiometers l and 25) is effected via a servo-control systemduring fluoroscopic examination, the invention may also be used in X-rayapparatus in which this displacement is performed by means of a motornot provided with servo-control and in which consequently the controlcircuit of the servo-control system is interrupted during fluoroscopicexamination (thus the servo-control system operates only after thechange-over to radiographic operation). The tappings on thepotentiometers l4 and 24 should of course in the case to be displaced bythe motors l2 and 22 respectively.

What is claimed is:

1. In X-ray apparatus having both fluoroscopy and radiography capabilityand having an adjustable diaphragm controlling the X-ray beam size,apparatus for controlling said adjustable diaphragm and for alerting anoperator when the display during fluoroscopy is larger than what wouldbe recorded during radiography, comprising:

a servo system controlling said adjustable diaphragm in accordance withan input signal supplied thereto;

means for producing a first signal which when supplied as said inputsignal to said servo system causes said servo system to adjust saiddiaphragm so as to conform the size of the X-ray beam to the size of theradiographic film in said X-ray apparatus',

means for producing a manually variable second signal which whensupplied as said input signal to said servo system causes said servosystem to adjust said diaphragm to a variable size in accordance withsaid manually variable second signal;

switching means for supplying as said input signal to said servo systemduring fluoroscopy said second signal and during radiography said firstsignal;

comparing means responsive to said first and second signals duringfluoroscopy for producing a suitable output signal when the beam sizewhich corresponds to said second signal exceeds the beam size whichcorresponds to said first signal; and

visual indicating means responsive to said output signal for alerting anoperator that the display during fluoroscopy is larger than what wouldbe recorded during radiography.

2. ln X-ray apparatus having both fluoroscopy and radiography capabilityand having a diaphragm adjust able separately in two dimensionscontrolling the X-ray beam size separately in two dimensions, apparatusfor separately controlling said diaphragm in each of said two dimensionsand for alerting an operator when the display during fluoroscopy islarger in either of said dimensions than what would be recorded duringradiography, comprising for each of said two dimensions the elements ofclaim 1.

3. Apparatus as defined in claim 2 wherein said visual indicating meansfor each of said two dimensions is the same visual indicating means.said same visual indicating means being responsive to said output signalcorresponding to either of said two dimensions.

1. In X-ray apparatus having both fluoroscopy and radiography capabilityand having an adjustable diaphragm controlling the Xray beam size,apparatus for controlling said adjustable diaphragm and for alerting anoperator when the display during fluoroscopy is larger than what wouldbe recorded during radiography, comprising: a servo system controllingsaid adjustable diaphragm in accordance with an input signal suppliedthereto; means for producing a first signal which when supplied as saidinput signal to said servo system causes said servo system to adjustsaid diaphragm so as to conform the size of the X-ray beam to the sizeof the radiographic film in said X-ray apparatus; means for producing amanually variable second signal which when supplied as said input signalto said servo system causes said servo system to adjust said diaphragmto a variable size in accordance with said manually variable secondsignal; switching means for supplying as said input signal to said servosystem during fluoroscopy said second signal and during radiography saidfirst signal; comparing means responsive to said first and secondsignals during fluoroscopy for producing a suitable output signal whenthe beam size which corresponds to said second signal exceeds the beamsize which corresponds to said first signal; and visual indicating meansresponsive to said output signal for alerting an operator that thedisplay during fluoroscopy is larger than what would be recorded duringradiography.
 2. In X-ray apparatus having both fluoroscopy andradiography capability and having a diaphragm adjustable separately intwo dimensions controlling the X-ray beam size separately in twodimensions, apparatus for separately controlling said diaphragm in eachof said two dimensions and for alerting an operator when the displayduring fluoroscopy is larger in either of said dimensions than whatwould be recorded during radiography, comprising for each of said twodimensions the elements of claim
 3. Apparatus as defined in claim 2wherein said visual indicating means for each of said two dimensions isthe same visual indicating means, said same visual indicating meansbeing responsive to said output signal corresponding to either of saidtwo dimensions.